include/sys/arc_impl.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2013 by Delphix. All rights reserved.
  24  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  25  * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
  26  */
  27
  28 #ifndef _SYS_ARC_IMPL_H
  29 #define _SYS_ARC_IMPL_H
  30
  31 #include <sys/arc.h>
  32 #include <sys/zio_crypt.h>
  33 #include <sys/zthr.h>
  34 #include <sys/aggsum.h>
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 /*
  41  * Note that buffers can be in one of 6 states:
  42  *      ARC_anon        - anonymous (discussed below)
  43  *      ARC_mru         - recently used, currently cached
  44  *      ARC_mru_ghost   - recently used, no longer in cache
  45  *      ARC_mfu         - frequently used, currently cached
  46  *      ARC_mfu_ghost   - frequently used, no longer in cache
  47  *      ARC_l2c_only    - exists in L2ARC but not other states
  48  * When there are no active references to the buffer, they are
  49  * are linked onto a list in one of these arc states.  These are
  50  * the only buffers that can be evicted or deleted.  Within each
  51  * state there are multiple lists, one for meta-data and one for
  52  * non-meta-data.  Meta-data (indirect blocks, blocks of dnodes,
  53  * etc.) is tracked separately so that it can be managed more
  54  * explicitly: favored over data, limited explicitly.
  55  *
  56  * Anonymous buffers are buffers that are not associated with
  57  * a DVA.  These are buffers that hold dirty block copies
  58  * before they are written to stable storage.  By definition,
  59  * they are "ref'd" and are considered part of arc_mru
  60  * that cannot be freed.  Generally, they will acquire a DVA
  61  * as they are written and migrate onto the arc_mru list.
  62  *
  63  * The ARC_l2c_only state is for buffers that are in the second
  64  * level ARC but no longer in any of the ARC_m* lists.  The second
  65  * level ARC itself may also contain buffers that are in any of
  66  * the ARC_m* states - meaning that a buffer can exist in two
  67  * places.  The reason for the ARC_l2c_only state is to keep the
  68  * buffer header in the hash table, so that reads that hit the
  69  * second level ARC benefit from these fast lookups.
  70  */
  71
  72 typedef struct arc_state {
  73         /*
  74          * list of evictable buffers
  75          */
  76         multilist_t *arcs_list[ARC_BUFC_NUMTYPES];
  77         /*
  78          * total amount of evictable data in this state
  79          */
  80         zfs_refcount_t arcs_esize[ARC_BUFC_NUMTYPES];
  81         /*
  82          * total amount of data in this state; this includes: evictable,
  83          * non-evictable, ARC_BUFC_DATA, and ARC_BUFC_METADATA.
  84          */
  85         zfs_refcount_t arcs_size;
  86         /*
  87          * supports the "dbufs" kstat
  88          */
  89         arc_state_type_t arcs_state;
  90 } arc_state_t;
  91
  92 typedef struct arc_callback arc_callback_t;
  93
  94 struct arc_callback {
  95         void                    *acb_private;
  96         arc_read_done_func_t    *acb_done;
  97         arc_buf_t               *acb_buf;
  98         boolean_t               acb_encrypted;
  99         boolean_t               acb_compressed;
 100         boolean_t               acb_noauth;
 101         zbookmark_phys_t        acb_zb;
 102         zio_t                   *acb_zio_dummy;
 103         zio_t                   *acb_zio_head;
 104         arc_callback_t          *acb_next;
 105 };
 106
 107 typedef struct arc_write_callback arc_write_callback_t;
 108
 109 struct arc_write_callback {
 110         void                    *awcb_private;
 111         arc_write_done_func_t   *awcb_ready;
 112         arc_write_done_func_t   *awcb_children_ready;
 113         arc_write_done_func_t   *awcb_physdone;
 114         arc_write_done_func_t   *awcb_done;
 115         arc_buf_t               *awcb_buf;
 116 };
 117
 118 /*
 119  * ARC buffers are separated into multiple structs as a memory saving measure:
 120  *   - Common fields struct, always defined, and embedded within it:
 121  *       - L2-only fields, always allocated but undefined when not in L2ARC
 122  *       - L1-only fields, only allocated when in L1ARC
 123  *
 124  *           Buffer in L1                     Buffer only in L2
 125  *    +------------------------+          +------------------------+
 126  *    | arc_buf_hdr_t          |          | arc_buf_hdr_t          |
 127  *    |                        |          |                        |
 128  *    |                        |          |                        |
 129  *    |                        |          |                        |
 130  *    +------------------------+          +------------------------+
 131  *    | l2arc_buf_hdr_t        |          | l2arc_buf_hdr_t        |
 132  *    | (undefined if L1-only) |          |                        |
 133  *    +------------------------+          +------------------------+
 134  *    | l1arc_buf_hdr_t        |
 135  *    |                        |
 136  *    |                        |
 137  *    |                        |
 138  *    |                        |
 139  *    +------------------------+
 140  *
 141  * Because it's possible for the L2ARC to become extremely large, we can wind
 142  * up eating a lot of memory in L2ARC buffer headers, so the size of a header
 143  * is minimized by only allocating the fields necessary for an L1-cached buffer
 144  * when a header is actually in the L1 cache. The sub-headers (l1arc_buf_hdr and
 145  * l2arc_buf_hdr) are embedded rather than allocated separately to save a couple
 146  * words in pointers. arc_hdr_realloc() is used to switch a header between
 147  * these two allocation states.
 148  */
 149 typedef struct l1arc_buf_hdr {
 150         kmutex_t                b_freeze_lock;
 151         zio_cksum_t             *b_freeze_cksum;
 152
 153         arc_buf_t               *b_buf;
 154         uint32_t                b_bufcnt;
 155         /* for waiting on writes to complete */
 156         kcondvar_t              b_cv;
 157         uint8_t                 b_byteswap;
 158
 159
 160         /* protected by arc state mutex */
 161         arc_state_t             *b_state;
 162         multilist_node_t        b_arc_node;
 163
 164         /* updated atomically */
 165         clock_t                 b_arc_access;
 166         uint32_t                b_mru_hits;
 167         uint32_t                b_mru_ghost_hits;
 168         uint32_t                b_mfu_hits;
 169         uint32_t                b_mfu_ghost_hits;
 170         uint32_t                b_l2_hits;
 171
 172         /* self protecting */
 173         zfs_refcount_t          b_refcnt;
 174
 175         arc_callback_t          *b_acb;
 176         abd_t                   *b_pabd;
 177 } l1arc_buf_hdr_t;
 178
 179 /*
 180  * Encrypted blocks will need to be stored encrypted on the L2ARC
 181  * disk as they appear in the main pool. In order for this to work we
 182  * need to pass around the encryption parameters so they can be used
 183  * to write data to the L2ARC. This struct is only defined in the
 184  * arc_buf_hdr_t if the L1 header is defined and has the ARC_FLAG_ENCRYPTED
 185  * flag set.
 186  */
 187 typedef struct arc_buf_hdr_crypt {
 188         abd_t                   *b_rabd;        /* raw encrypted data */
 189         dmu_object_type_t       b_ot;           /* object type */
 190         uint32_t                b_ebufcnt;      /* count of encrypted buffers */
 191
 192         /* dsobj for looking up encryption key for l2arc encryption */
 193         uint64_t                b_dsobj;
 194
 195         /* encryption parameters */
 196         uint8_t                 b_salt[ZIO_DATA_SALT_LEN];
 197         uint8_t                 b_iv[ZIO_DATA_IV_LEN];
 198
 199         /*
 200          * Technically this could be removed since we will always be able to
 201          * get the mac from the bp when we need it. However, it is inconvenient
 202          * for callers of arc code to have to pass a bp in all the time. This
 203          * also allows us to assert that L2ARC data is properly encrypted to
 204          * match the data in the main storage pool.
 205          */
 206         uint8_t                 b_mac[ZIO_DATA_MAC_LEN];
 207 } arc_buf_hdr_crypt_t;
 208
 209 typedef struct l2arc_dev {
 210         vdev_t                  *l2ad_vdev;     /* vdev */
 211         spa_t                   *l2ad_spa;      /* spa */
 212         uint64_t                l2ad_hand;      /* next write location */
 213         uint64_t                l2ad_start;     /* first addr on device */
 214         uint64_t                l2ad_end;       /* last addr on device */
 215         boolean_t               l2ad_first;     /* first sweep through */
 216         boolean_t               l2ad_writing;   /* currently writing */
 217         kmutex_t                l2ad_mtx;       /* lock for buffer list */
 218         list_t                  l2ad_buflist;   /* buffer list */
 219         list_node_t             l2ad_node;      /* device list node */
 220         zfs_refcount_t          l2ad_alloc;     /* allocated bytes */
 221 } l2arc_dev_t;
 222
 223 typedef struct l2arc_buf_hdr {
 224         /* protected by arc_buf_hdr mutex */
 225         l2arc_dev_t             *b_dev;         /* L2ARC device */
 226         uint64_t                b_daddr;        /* disk address, offset byte */
 227         uint32_t                b_hits;
 228
 229         list_node_t             b_l2node;
 230 } l2arc_buf_hdr_t;
 231
 232 typedef struct l2arc_write_callback {
 233         l2arc_dev_t     *l2wcb_dev;             /* device info */
 234         arc_buf_hdr_t   *l2wcb_head;            /* head of write buflist */
 235 } l2arc_write_callback_t;
 236
 237 struct arc_buf_hdr {
 238         /* protected by hash lock */
 239         dva_t                   b_dva;
 240         uint64_t                b_birth;
 241
 242         arc_buf_contents_t      b_type;
 243         arc_buf_hdr_t           *b_hash_next;
 244         arc_flags_t             b_flags;
 245
 246         /*
 247          * This field stores the size of the data buffer after
 248          * compression, and is set in the arc's zio completion handlers.
 249          * It is in units of SPA_MINBLOCKSIZE (e.g. 1 == 512 bytes).
 250          *
 251          * While the block pointers can store up to 32MB in their psize
 252          * field, we can only store up to 32MB minus 512B. This is due
 253          * to the bp using a bias of 1, whereas we use a bias of 0 (i.e.
 254          * a field of zeros represents 512B in the bp). We can't use a
 255          * bias of 1 since we need to reserve a psize of zero, here, to
 256          * represent holes and embedded blocks.
 257          *
 258          * This isn't a problem in practice, since the maximum size of a
 259          * buffer is limited to 16MB, so we never need to store 32MB in
 260          * this field. Even in the upstream illumos code base, the
 261          * maximum size of a buffer is limited to 16MB.
 262          */
 263         uint16_t                b_psize;
 264
 265         /*
 266          * This field stores the size of the data buffer before
 267          * compression, and cannot change once set. It is in units
 268          * of SPA_MINBLOCKSIZE (e.g. 2 == 1024 bytes)
 269          */
 270         uint16_t                b_lsize;        /* immutable */
 271         uint64_t                b_spa;          /* immutable */
 272
 273         /* L2ARC fields. Undefined when not in L2ARC. */
 274         l2arc_buf_hdr_t         b_l2hdr;
 275         /* L1ARC fields. Undefined when in l2arc_only state */
 276         l1arc_buf_hdr_t         b_l1hdr;
 277         /*
 278          * Encryption parameters. Defined only when ARC_FLAG_ENCRYPTED
 279          * is set and the L1 header exists.
 280          */
 281         arc_buf_hdr_crypt_t b_crypt_hdr;
 282 };
 283
 284 typedef struct arc_stats {
 285         kstat_named_t arcstat_hits;
 286         kstat_named_t arcstat_misses;
 287         kstat_named_t arcstat_demand_data_hits;
 288         kstat_named_t arcstat_demand_data_misses;
 289         kstat_named_t arcstat_demand_metadata_hits;
 290         kstat_named_t arcstat_demand_metadata_misses;
 291         kstat_named_t arcstat_prefetch_data_hits;
 292         kstat_named_t arcstat_prefetch_data_misses;
 293         kstat_named_t arcstat_prefetch_metadata_hits;
 294         kstat_named_t arcstat_prefetch_metadata_misses;
 295         kstat_named_t arcstat_mru_hits;
 296         kstat_named_t arcstat_mru_ghost_hits;
 297         kstat_named_t arcstat_mfu_hits;
 298         kstat_named_t arcstat_mfu_ghost_hits;
 299         kstat_named_t arcstat_deleted;
 300         /*
 301          * Number of buffers that could not be evicted because the hash lock
 302          * was held by another thread.  The lock may not necessarily be held
 303          * by something using the same buffer, since hash locks are shared
 304          * by multiple buffers.
 305          */
 306         kstat_named_t arcstat_mutex_miss;
 307         /*
 308          * Number of buffers skipped when updating the access state due to the
 309          * header having already been released after acquiring the hash lock.
 310          */
 311         kstat_named_t arcstat_access_skip;
 312         /*
 313          * Number of buffers skipped because they have I/O in progress, are
 314          * indirect prefetch buffers that have not lived long enough, or are
 315          * not from the spa we're trying to evict from.
 316          */
 317         kstat_named_t arcstat_evict_skip;
 318         /*
 319          * Number of times arc_evict_state() was unable to evict enough
 320          * buffers to reach its target amount.
 321          */
 322         kstat_named_t arcstat_evict_not_enough;
 323         kstat_named_t arcstat_evict_l2_cached;
 324         kstat_named_t arcstat_evict_l2_eligible;
 325         kstat_named_t arcstat_evict_l2_ineligible;
 326         kstat_named_t arcstat_evict_l2_skip;
 327         kstat_named_t arcstat_hash_elements;
 328         kstat_named_t arcstat_hash_elements_max;
 329         kstat_named_t arcstat_hash_collisions;
 330         kstat_named_t arcstat_hash_chains;
 331         kstat_named_t arcstat_hash_chain_max;
 332         kstat_named_t arcstat_p;
 333         kstat_named_t arcstat_c;
 334         kstat_named_t arcstat_c_min;
 335         kstat_named_t arcstat_c_max;
 336         /* Not updated directly; only synced in arc_kstat_update. */
 337         kstat_named_t arcstat_size;
 338         /*
 339          * Number of compressed bytes stored in the arc_buf_hdr_t's b_pabd.
 340          * Note that the compressed bytes may match the uncompressed bytes
 341          * if the block is either not compressed or compressed arc is disabled.
 342          */
 343         kstat_named_t arcstat_compressed_size;
 344         /*
 345          * Uncompressed size of the data stored in b_pabd. If compressed
 346          * arc is disabled then this value will be identical to the stat
 347          * above.
 348          */
 349         kstat_named_t arcstat_uncompressed_size;
 350         /*
 351          * Number of bytes stored in all the arc_buf_t's. This is classified
 352          * as "overhead" since this data is typically short-lived and will
 353          * be evicted from the arc when it becomes unreferenced unless the
 354          * zfs_keep_uncompressed_metadata or zfs_keep_uncompressed_level
 355          * values have been set (see comment in dbuf.c for more information).
 356          */
 357         kstat_named_t arcstat_overhead_size;
 358         /*
 359          * Number of bytes consumed by internal ARC structures necessary
 360          * for tracking purposes; these structures are not actually
 361          * backed by ARC buffers. This includes arc_buf_hdr_t structures
 362          * (allocated via arc_buf_hdr_t_full and arc_buf_hdr_t_l2only
 363          * caches), and arc_buf_t structures (allocated via arc_buf_t
 364          * cache).
 365          * Not updated directly; only synced in arc_kstat_update.
 366          */
 367         kstat_named_t arcstat_hdr_size;
 368         /*
 369          * Number of bytes consumed by ARC buffers of type equal to
 370          * ARC_BUFC_DATA. This is generally consumed by buffers backing
 371          * on disk user data (e.g. plain file contents).
 372          * Not updated directly; only synced in arc_kstat_update.
 373          */
 374         kstat_named_t arcstat_data_size;
 375         /*
 376          * Number of bytes consumed by ARC buffers of type equal to
 377          * ARC_BUFC_METADATA. This is generally consumed by buffers
 378          * backing on disk data that is used for internal ZFS
 379          * structures (e.g. ZAP, dnode, indirect blocks, etc).
 380          * Not updated directly; only synced in arc_kstat_update.
 381          */
 382         kstat_named_t arcstat_metadata_size;
 383         /*
 384          * Number of bytes consumed by dmu_buf_impl_t objects.
 385          * Not updated directly; only synced in arc_kstat_update.
 386          */
 387         kstat_named_t arcstat_dbuf_size;
 388         /*
 389          * Number of bytes consumed by dnode_t objects.
 390          * Not updated directly; only synced in arc_kstat_update.
 391          */
 392         kstat_named_t arcstat_dnode_size;
 393         /*
 394          * Number of bytes consumed by bonus buffers.
 395          * Not updated directly; only synced in arc_kstat_update.
 396          */
 397         kstat_named_t arcstat_bonus_size;
 398         /*
 399          * Total number of bytes consumed by ARC buffers residing in the
 400          * arc_anon state. This includes *all* buffers in the arc_anon
 401          * state; e.g. data, metadata, evictable, and unevictable buffers
 402          * are all included in this value.
 403          * Not updated directly; only synced in arc_kstat_update.
 404          */
 405         kstat_named_t arcstat_anon_size;
 406         /*
 407          * Number of bytes consumed by ARC buffers that meet the
 408          * following criteria: backing buffers of type ARC_BUFC_DATA,
 409          * residing in the arc_anon state, and are eligible for eviction
 410          * (e.g. have no outstanding holds on the buffer).
 411          * Not updated directly; only synced in arc_kstat_update.
 412          */
 413         kstat_named_t arcstat_anon_evictable_data;
 414         /*
 415          * Number of bytes consumed by ARC buffers that meet the
 416          * following criteria: backing buffers of type ARC_BUFC_METADATA,
 417          * residing in the arc_anon state, and are eligible for eviction
 418          * (e.g. have no outstanding holds on the buffer).
 419          * Not updated directly; only synced in arc_kstat_update.
 420          */
 421         kstat_named_t arcstat_anon_evictable_metadata;
 422         /*
 423          * Total number of bytes consumed by ARC buffers residing in the
 424          * arc_mru state. This includes *all* buffers in the arc_mru
 425          * state; e.g. data, metadata, evictable, and unevictable buffers
 426          * are all included in this value.
 427          * Not updated directly; only synced in arc_kstat_update.
 428          */
 429         kstat_named_t arcstat_mru_size;
 430         /*
 431          * Number of bytes consumed by ARC buffers that meet the
 432          * following criteria: backing buffers of type ARC_BUFC_DATA,
 433          * residing in the arc_mru state, and are eligible for eviction
 434          * (e.g. have no outstanding holds on the buffer).
 435          * Not updated directly; only synced in arc_kstat_update.
 436          */
 437         kstat_named_t arcstat_mru_evictable_data;
 438         /*
 439          * Number of bytes consumed by ARC buffers that meet the
 440          * following criteria: backing buffers of type ARC_BUFC_METADATA,
 441          * residing in the arc_mru state, and are eligible for eviction
 442          * (e.g. have no outstanding holds on the buffer).
 443          * Not updated directly; only synced in arc_kstat_update.
 444          */
 445         kstat_named_t arcstat_mru_evictable_metadata;
 446         /*
 447          * Total number of bytes that *would have been* consumed by ARC
 448          * buffers in the arc_mru_ghost state. The key thing to note
 449          * here, is the fact that this size doesn't actually indicate
 450          * RAM consumption. The ghost lists only consist of headers and
 451          * don't actually have ARC buffers linked off of these headers.
 452          * Thus, *if* the headers had associated ARC buffers, these
 453          * buffers *would have* consumed this number of bytes.
 454          * Not updated directly; only synced in arc_kstat_update.
 455          */
 456         kstat_named_t arcstat_mru_ghost_size;
 457         /*
 458          * Number of bytes that *would have been* consumed by ARC
 459          * buffers that are eligible for eviction, of type
 460          * ARC_BUFC_DATA, and linked off the arc_mru_ghost state.
 461          * Not updated directly; only synced in arc_kstat_update.
 462          */
 463         kstat_named_t arcstat_mru_ghost_evictable_data;
 464         /*
 465          * Number of bytes that *would have been* consumed by ARC
 466          * buffers that are eligible for eviction, of type
 467          * ARC_BUFC_METADATA, and linked off the arc_mru_ghost state.
 468          * Not updated directly; only synced in arc_kstat_update.
 469          */
 470         kstat_named_t arcstat_mru_ghost_evictable_metadata;
 471         /*
 472          * Total number of bytes consumed by ARC buffers residing in the
 473          * arc_mfu state. This includes *all* buffers in the arc_mfu
 474          * state; e.g. data, metadata, evictable, and unevictable buffers
 475          * are all included in this value.
 476          * Not updated directly; only synced in arc_kstat_update.
 477          */
 478         kstat_named_t arcstat_mfu_size;
 479         /*
 480          * Number of bytes consumed by ARC buffers that are eligible for
 481          * eviction, of type ARC_BUFC_DATA, and reside in the arc_mfu
 482          * state.
 483          * Not updated directly; only synced in arc_kstat_update.
 484          */
 485         kstat_named_t arcstat_mfu_evictable_data;
 486         /*
 487          * Number of bytes consumed by ARC buffers that are eligible for
 488          * eviction, of type ARC_BUFC_METADATA, and reside in the
 489          * arc_mfu state.
 490          * Not updated directly; only synced in arc_kstat_update.
 491          */
 492         kstat_named_t arcstat_mfu_evictable_metadata;
 493         /*
 494          * Total number of bytes that *would have been* consumed by ARC
 495          * buffers in the arc_mfu_ghost state. See the comment above
 496          * arcstat_mru_ghost_size for more details.
 497          * Not updated directly; only synced in arc_kstat_update.
 498          */
 499         kstat_named_t arcstat_mfu_ghost_size;
 500         /*
 501          * Number of bytes that *would have been* consumed by ARC
 502          * buffers that are eligible for eviction, of type
 503          * ARC_BUFC_DATA, and linked off the arc_mfu_ghost state.
 504          * Not updated directly; only synced in arc_kstat_update.
 505          */
 506         kstat_named_t arcstat_mfu_ghost_evictable_data;
 507         /*
 508          * Number of bytes that *would have been* consumed by ARC
 509          * buffers that are eligible for eviction, of type
 510          * ARC_BUFC_METADATA, and linked off the arc_mru_ghost state.
 511          * Not updated directly; only synced in arc_kstat_update.
 512          */
 513         kstat_named_t arcstat_mfu_ghost_evictable_metadata;
 514         kstat_named_t arcstat_l2_hits;
 515         kstat_named_t arcstat_l2_misses;
 516         kstat_named_t arcstat_l2_feeds;
 517         kstat_named_t arcstat_l2_rw_clash;
 518         kstat_named_t arcstat_l2_read_bytes;
 519         kstat_named_t arcstat_l2_write_bytes;
 520         kstat_named_t arcstat_l2_writes_sent;
 521         kstat_named_t arcstat_l2_writes_done;
 522         kstat_named_t arcstat_l2_writes_error;
 523         kstat_named_t arcstat_l2_writes_lock_retry;
 524         kstat_named_t arcstat_l2_evict_lock_retry;
 525         kstat_named_t arcstat_l2_evict_reading;
 526         kstat_named_t arcstat_l2_evict_l1cached;
 527         kstat_named_t arcstat_l2_free_on_write;
 528         kstat_named_t arcstat_l2_abort_lowmem;
 529         kstat_named_t arcstat_l2_cksum_bad;
 530         kstat_named_t arcstat_l2_io_error;
 531         kstat_named_t arcstat_l2_lsize;
 532         kstat_named_t arcstat_l2_psize;
 533         /* Not updated directly; only synced in arc_kstat_update. */
 534         kstat_named_t arcstat_l2_hdr_size;
 535         kstat_named_t arcstat_memory_throttle_count;
 536         kstat_named_t arcstat_memory_direct_count;
 537         kstat_named_t arcstat_memory_indirect_count;
 538         kstat_named_t arcstat_memory_all_bytes;
 539         kstat_named_t arcstat_memory_free_bytes;
 540         kstat_named_t arcstat_memory_available_bytes;
 541         kstat_named_t arcstat_no_grow;
 542         kstat_named_t arcstat_tempreserve;
 543         kstat_named_t arcstat_loaned_bytes;
 544         kstat_named_t arcstat_prune;
 545         /* Not updated directly; only synced in arc_kstat_update. */
 546         kstat_named_t arcstat_meta_used;
 547         kstat_named_t arcstat_meta_limit;
 548         kstat_named_t arcstat_dnode_limit;
 549         kstat_named_t arcstat_meta_max;
 550         kstat_named_t arcstat_meta_min;
 551         kstat_named_t arcstat_async_upgrade_sync;
 552         kstat_named_t arcstat_demand_hit_predictive_prefetch;
 553         kstat_named_t arcstat_demand_hit_prescient_prefetch;
 554         kstat_named_t arcstat_need_free;
 555         kstat_named_t arcstat_sys_free;
 556         kstat_named_t arcstat_raw_size;
 557         kstat_named_t arcstat_cached_only_in_progress;
 558 } arc_stats_t;
 559
 560 typedef enum free_memory_reason_t {
 561         FMR_UNKNOWN,
 562         FMR_NEEDFREE,
 563         FMR_LOTSFREE,
 564         FMR_SWAPFS_MINFREE,
 565         FMR_PAGES_PP_MAXIMUM,
 566         FMR_HEAP_ARENA,
 567         FMR_ZIO_ARENA,
 568 } free_memory_reason_t;
 569
 570 #define ARCSTAT(stat)   (arc_stats.stat.value.ui64)
 571
 572 #define ARCSTAT_INCR(stat, val) \
 573         atomic_add_64(&arc_stats.stat.value.ui64, (val))
 574
 575 #define ARCSTAT_BUMP(stat)      ARCSTAT_INCR(stat, 1)
 576 #define ARCSTAT_BUMPDOWN(stat)  ARCSTAT_INCR(stat, -1)
 577
 578 #define arc_no_grow     ARCSTAT(arcstat_no_grow) /* do not grow cache size */
 579 #define arc_p           ARCSTAT(arcstat_p)      /* target size of MRU */
 580 #define arc_c           ARCSTAT(arcstat_c)      /* target size of cache */
 581 #define arc_c_min       ARCSTAT(arcstat_c_min)  /* min target cache size */
 582 #define arc_c_max       ARCSTAT(arcstat_c_max)  /* max target cache size */
 583 #define arc_sys_free    ARCSTAT(arcstat_sys_free) /* target system free bytes */
 584 #define arc_need_free   ARCSTAT(arcstat_need_free) /* bytes to be freed */
 585
 586 extern int arc_zio_arena_free_shift;
 587 extern taskq_t *arc_prune_taskq;
 588 extern arc_stats_t arc_stats;
 589 extern hrtime_t arc_growtime;
 590 extern boolean_t arc_warm;
 591 extern int arc_grow_retry;
 592 extern int arc_shrink_shift;
 593 extern zthr_t           *arc_adjust_zthr;
 594 extern kmutex_t         arc_adjust_lock;
 595 extern kcondvar_t       arc_adjust_waiters_cv;
 596 extern boolean_t        arc_adjust_needed;
 597 extern kmutex_t arc_prune_mtx;
 598 extern list_t arc_prune_list;
 599 extern aggsum_t arc_size;
 600 extern arc_state_t      *arc_mfu;
 601 extern arc_state_t      *arc_mru;
 602 extern uint_t zfs_arc_pc_percent;
 603 extern int arc_lotsfree_percent;
 604
 605 extern void arc_reduce_target_size(int64_t to_free);
 606 extern boolean_t arc_reclaim_needed(void);
 607 extern void arc_kmem_reap_soon(void);
 608
 609 extern void arc_lowmem_init(void);
 610 extern void arc_lowmem_fini(void);
 611 extern void arc_prune_async(int64_t);
 612 extern int arc_memory_throttle(spa_t *spa, uint64_t reserve, uint64_t txg);
 613 extern uint64_t arc_free_memory(void);
 614 extern int64_t arc_available_memory(void);
 615 extern void arc_tuning_update(void);
 616
 617 extern int param_set_arc_long(ZFS_MODULE_PARAM_ARGS);
 618 extern int param_set_arc_int(ZFS_MODULE_PARAM_ARGS);
 619
 620 #ifdef __cplusplus
 621 }
 622 #endif
 623
 624 #endif /* _SYS_ARC_IMPL_H */